At a hybrid vehicle having an engine and an electric motor mounted as the source of vehicle driving power, charging and discharging of a power storage device is controlled such that the SOC (State of Charge) of the power storage device (typically, a battery) is maintained within a predetermined control range in a running mode with the engine operating.
Japanese Patent Laying-Open No. 2002-51405 (PTD 1) discloses modifying the setting range of the remaining amount (SOC) of a power storage device (battery) allowing charging/discharging thereof according to a vehicle state. Specifically, the control of modifying the SOC control range based on a signal applied from a 3D gyro sensor, and control of modifying the SOC control range in response to a user switch and/or an operation of the accelerator or brakes are disclosed.
Japanese Patent Publication No. 3827980 (PTD 2) discloses, at a hybrid vehicle incorporating an electric motor generating assist torque, setting the assist amount according to a control manner differing for each regional zone provided for the remaining amount (SOC) in a power storage device. Particularly, providing a predetermined transitional usage region between a charging/discharging allowed region and a discharging suppressed region, and control of rendering the assist amount variable by the electric motor according to the SOC in the relevant transitional usage region are disclosed.
Japanese Patent Laying-Open No. 2001-69602 (PTD 3) discloses battery charging and discharging control at a hybrid vehicle that includes an engine, a motor generating driving power to assist the output of the engine, and a battery to which is charged electrical energy obtained by operating the motor as a power generator when the assisting driving power by the motor is not required. Specifically, control of allowing only discharging, when the temperature of the battery is higher than a predetermined temperature, until the SOC of the battery attains a predetermined value is disclosed. Accordingly, charging at a temperature region where the charging efficiency is degraded is prohibited to prevent battery degradation.
Japanese Patent Laying-Open No. 2001-169408 (PTD 4) discloses control to carry out regenerative charging and discharging efficiently for a hybrid vehicle is disclosed. Particularly, based on the battery SOC and road information including the current value information of the vehicle and high level information during the running route, the upper limit of allowing battery discharging is set such that the battery SOC attains the minimum value at the highest peak point on the running route.